The use of the compounds employed in the present invention in the enhancement of serum and tissue zinc levels is described in copending U.S. application Ser. No. 765,420, filed Jan. 21, 1977. There is some evidence in the literature that zinc may have a protective role in certain cardiovascular related disorders and possibly in hypertension. (See, for example, Medical Clinics of North America 58, no. 2, 381 (1974)). Although it has been found that the .alpha.-mercapto-.beta.-arylacrylic acids employed in the present invention enhance serum and tissue levels of zinc, the exact mechanism of action of the herein described .alpha.-mercapto-.beta.-arylacrylic acids in the treatment of hypertension has not been delineated.
While .alpha.-mercapto-.beta.-arylacrylic acids are well known, their utilization in therapeutics is exceedingly rare. We have made the unexpected discovery that the .alpha.-mercapto-.beta.-arylacrylic acids described herein are useful in the treatment of hypertension. These compounds are most commonly prepared by the procedure of Campaigne, E. and Cline, R., J. Org. Chem. 21, 32 (1956) from rhodanine and the corresponding aryl aldehydes. U.S. Pat. No. 3,452,039 describes a number of .alpha.-mercapto-.beta.-arylacrylic acids and their substitution products utilized as intermediates in the manufacture of benzothiophene hypocholesterolemic agents. Various .alpha.-mercapto-.beta.-arylacrylic acids were prepared and tested by Ravazzoni, C., et al., Ann. Chim. (Rome) 52 305-12 (1962), Chem. Abst. 57, 9833g, and reported to be effective plant growth substances. Haskel, et al., J. Med. Chem. 13 697 (1970) prepared and tested .alpha.-mercapto-.beta.-arylacrylic acids including substituted phenyl, substituted thienyl and substituted pyridyl analogs for neuraminidase inhibition and administered the most potent enzyme inhibitors, for example, .alpha.-mercapto-.beta.-4-nitrophenyl acrylic acid orally and intraperitoneally to mice without increase in survival against influenza virus. Being interested in antibacterial and antifungal activity Foy, et al., J. Pharm. Sci. 61 1209 (1972) tested .alpha.-mercaptocinnamic acid as having some activity in this regard and incidentally relatively weak metal binding activity for copper, aluminum and iron. Activity in vitro in inhibiting rat heart mitochrondia pyruvate transport was reported for .alpha.-thio-2-furanopyruvate, otherwise named .alpha.-mercapto-.beta.-2-furylacrylic acid by Halestrap, A., Biochem. J. 148 (1) 85 (1975) at page 90. No references more pertinent than these are known to applicants.